Yarn feed mechanism with constant throughput and pneumatic tension regulation

ABSTRACT

This invention is directed to obtaining and maintaining a constant tension on yarn being taken from a spool thereof and directed to a sewing needle, effected by employing a constant speed roller revolvaly driven around an axis variably movable to and fro relative to fixed yarn guides before and after the roller, movement of the axis away from the guides placing greater tension on the yarn and moving toward the guides (or toward an intermediate position between the guides) lessening tension on the yarn, the movement of the axis being effected by force of high pressure or high leverage and being responsive to a minor low pressure initiatable of the high pressure system, the high pressure being constant but the valve(s) directing the flow of fluid for to and fro action of the axis being controlled by a piston-like valve responsive to the low pressure, and there being subsequent to the roller and guides in yarn-flow series a pulley mounted on one end of a lever arm pivoted on a fulcrum element about central of the arms length and at the opposite end of the arm there being a blade-valve for turning on and off the low pressure fluid to opposing bellows between which the fulcrum is mounted in suspension therebetween fixedly, whereby upon the tension on the yarn running around the pulley becoming greater or lesser, the blade-valve opens or closes to release low pressure fluid which released fluid moves the fulcrum upwardly or downwardly by effecting bellow action negatively and positively on the respective opposing bellows, while concurrently the released or terminated low pressure acts on the piston valve for turning on or off the high pressure for moving to or fro the axis of the roller between the fixed guides.

'[76] Inventor:

United States Patent I 1191 Leclercq YARN FEED MECHANISM WITH CONSTANT THROUGHPUT AND PNEUMATIC TENSION REGULATION Francis Leclercq, Chemin 21, No. 26, Tournai, Belgium 22 Filed: Dec. 23, 1971 21 Appl. No.: 211,533

Primary Examiner Allen N. Knowles Assistant Examiner-Gene A. Church AttorneyWilliam T. Hough et al.

[57] ABSTRACT This invention is directed to obtaining and maintaining a constant tension on yarn being taken from a spool thereof and directed to a sewing needle, effected by 1 1 July 17, 1973 employing a constant speed roller revolvaly driven around an axis variably movable to and fro relative to fixed yarn guides before and after the roller, movement of the axis away from the guides placing greater tension on the yarn and moving toward the guides (or toward an intermediate position between the guides) lessening tension on the yarn, the movement of the axis being effected by force of high pressure or high leverage and being responsive to a minor low pressure initiatable of the high pressure system, the high pressure being constant but the valve(s) directing the flow of fluid for to and fro action of the axis being controlled by a pistonlike valve responsive to the low pressure, and there being subsequent to the roller and guides in yarn-flow series a pulley mounted on one end of a lever arm pivoted on a fulcrum element about central of the arms length and at the opposite end of the arm there being a blade-valve for turning on and off the low pressure fluid to opposing bellows between which the fulcrum is mounted in suspension therebetween fixedly, whereby upon the tension on the yarn running around the pulley becoming greater or lesser, the blade-valve opens or closes to release low pressure fluid which released fluid moves the fulcrum upwardly or down-wardly by effecting bellow action negatively and positively on the respective opposing bellows, while concurrently the released or terminated low pressure acts on the piston valve for turning on or off the high pressure for moving to or fro the axis of the roller between the fixed guides.

3 Claims, 6 Drawing Figures Patented July 17, 1973 3,746,226

2 Sheets-Sheet 1 FIG.|

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FIG.3 E

Pat ented July 17, 1973 2 Sheets-Sheet 2 F IG.4

YARN FEED MECHANISM WITH CONSTANT THROUGHPUT AND PNEUMATIC TENSION REGULATION The present invention concerns a device for establishing and/or maintaining a relatively constant tension on yarn such as textile yarn or spun yarn, whatever the particular degree of elasticity of the yarn might be.

This system can be adapted to any textile machine whatsoever necessitating a yarn feed or delivery constant in throughput and tension, such as knitting machine, reel, winder, etc.

These three examples illustrate a possible application of the system without in any way limiting the range thereof.

The imperative requirement of constant throughput and tension must be achieved by a control or regulation which is as inexpensive as possible, the cost of which is comparable to the costs of the present systems and the assembly of which has a minimum bulk and is easily adaptable on any machine whatever.

There exist on the market numerous yarn feed systems specially for knitting machines. We have, for example, the following major types l cheek brakes or tension devices,

2 feed mechanism with bevel or cylindrical pinions,

3 capstan feed mechanism,

4 accumulation feed,

5 positive feed system (Rosen, CR3),

6 F.A.K. system.

Not all these systems are applicable to all types of yarn or spun yarn, ranging from the inelastic classic yarn to the elastomer, via the textured yarn certain of them being applicable only to one specific type of spun yarn, while' others, on the contrary, are absolutely unsuitable for no matter what type of spun yarn.

The system proposed does not come into one of the preceding categories. It is a question, indeed, of a pneumatic regulation of the tension of the yarn upstream of a wheel with constant velocity imposing a constant flow rate.

None of the classes of feed mechanisms listed above is comparable to the present invention. Indeed, the first five systems do not use a regulation (pneumatic or otherwise). Only the F.A.K. system utilizes a pneumatic regulation although designed differently. The F.A.K. system, adaptable only on a small circular machine with one or two feeds, performs the regulation of the tension downstream from the wheel imposing a constant flow rate. Furthermore, the regulation of the tension is effected by modification of the height of the feed cam.

In the case of a laboratory reel, for textured yarn for instance, a certain number of joining winds have to be wound around a winding cylinder in such a way that each wind has an identical length under a given load.

In order for a circular knitting machine with n feeds to produce a regular knitted fabric, the length of yarn absorbed per stitch, 1, must be constant from one needle to another and from one feed to another. This necessary condition is however not sufficient. It is known, indeed, that the variations in count, shade, waxing, twist, dye affinity, etc., may also provoke a defect in the direction of the courses of the article. This aspect of the problem is not to be taken into consideration in the present patent.

The yarn feed system on the knitting machine comprises the following different parts (FIG. 1).

The package B, the feed assembly F and the needle A. Suppose d, is the flow rate of the yarn at the exit of the feed mechanism, t the input tension of the yarn and t,, the output tension. In order to obtain a constant length of yarn absorbed per stitch, l, the flow rate d must be constant and the output tension t, must be constant and independent of r whatever may be the stresses exerted on the yarn upstream from the feed mechanism. In order to obtain a constant length of yarn absorbed per stitch, 1, from one feed to another, it is also necessary that the distance, a, between the needle butt (when the needle passes over the tip of the feed cam C and level of the needle beds n (or any other fixed mark) should be constant from one feed to another.

This condition may be obtained by a mechanical adjustment of the depth of the feed cam. On the assumption that wear prevents the concomitant adjustment of all the feed cams, an easy adjustment is obtained by checking exactly I, for a d constant at each feed.

In the case of a feed mechanism without control of the yarn tension, when the material stretches very slightly under a load which is not negligible (case of wool or cotton), the sudden changes in tension have no influence, or very little influence, on the throughput. If, on the contrary, the material may stretch to a considerable degree under slight load (case of textured yarns or elastomers), the sudden changes in tension will have an adverse influence on the throughput of the yarn, even if the latter is delivered at a constant velocity.

The feed mechanism is composed of two wheels D and T'the first of which, D, delivers a constant quantity of yarn for which the tension has been previously adjusted to as constant a value as possible by means of the wheel T (FIG. 1).

The regulation of the yarn tension, to a predetermined constant value, is effected essentially by variation of the linear velocity of the wheel T by comparison with the constant linear velocity of the wheel D. Any slipping between the wheels T or D and the yarn is excluded.

The variation of the linear velocity V of the yarn be effected by acting either on the angular velocity (u of the wheel T or on the value of the radius R of the wheel (V (all).

The assemblies efi'ected have shown that the methods permitting a modification of the value of the radius R do not give good results. For this purpose, one may use either a cone moving in relation to the fixed yarn, or a fixed cone on which the yarn moves, or a cylinder with variable radius R. The latter solution is technically expensive and rather difficult to execute. Not all these solutions give satisfaction, as it is necessary at the same time to ensure an adherence of the yarn on the wheel or cone to avoid any slipping, while permitting it a displacement in order to meet the variation in radius. Furthermore, the spun yarn lacks rigidity in order to react properly to a displacement control on a cone.

On the other hand, the assemblies utilizing the variation of angular velocity 10 give satisfaction and no longer present the drawbacks mentioned above. In order to minimize the cost of the apparatus, the rotary pneumatic motor and the electric motor are excluded.

This is the reason why a linear pneumatic motor or jack has been adopted and it is necessary to insert between the jack and the package T a speed variator controlled by the jack. The low pressure pneumatic regulation must be designed so as to avoid an overbulky jack as the latter is controlled by the jack must therefore necessitate only a slight effort to effect the controlled manoeuvre.

The two following variators are very suitable for the purpose required. However, in order to ensure greater facility of design and floor space, it is preferable to utilize the plate-pulley system rather than the reversecone variator.

FIGS. 2 and 3 show two possibilities for execution of the assembly. The plate-pulley system furthermore presents the advantage of easily permitting a modification of the throughput by simple displacement of the wheel D on the plate. This makes possible the easy adjustment of the system on machines which make knitted fabrics for which the feed must differ from one feeder to another (eg., Jacquard). The FIG. 2 embodiment diagrammatically illustrates that the yarn being run over the may be varied in the tension thereon by increasing or decreasing the relative speeds of one to the other of rollers T and D by virtue of opposingly dirrected cones mounted on the parallel axes of T and D as shown with the drive and speed of one of the axes being typically belt driven by the other through a belt enveloping both conical surfaces and the belt being subject to movement up and down the surfaces of the cones in axial direction in order to alter or vary the ratio of the driven belt, there being a suitable means for moving the interconnecting belt to and fro axially in response to a piston controlably moved to and fro upon negative and positive piston valve actuation by the comparator arm actuation and deactu-ation valve responsive to the tension or lack of tension on the pulley C which is mounted on the comparator arm pivoted on a fulcrum as illustrated in FIG. 1. The pneumatic part of the regulation comprises the following elements (FlG. 4) I l element'without monostable mobile piece which can operate under a maximum pressure of 200 g/sq.cm.

1 system blade-nozzle or displacement, translator 1 arm constituting the displacement comparator 1 jack 1 pressure stabilizing element or valve with pressure threshold (optional).

The feed pressure, after having passed by a filter Fl,- is reduced in a reducing valve D, to the pressure P, of 2 kg/sq.cm. (thus, very much higher then the nominal value) and in a reducing valve D to the pressure P, of 50 g/sq.cm. or 500 mm of water column.

The pressure P is then injected into the monostable element (E.M.) through the channel 1 whence the fluid is conveyed to channel 3 (Coanda effect) and emerges by the pipe 4 to be injected in the jack V. The piston rod is then completely out. The n monostable elements (E.M.), can be connected in the same way in parallel on the reducing valve D The pressure P at the exit of D is injected in a nozzle T, after having been stabilized by a pressure-threshold valve (optional in this assembly). Depending on whether or not the nozzle is sealed, we shall or shall not have a pressure in the pipe 6. This pressurizing of the pipe 6 will cause the fluid of the principal control of the element (E.M.) to tip from branch 3 to branch 2, i.e., from pipe 4 to 5. Finally, this is what controls the reentry movement of the jack rod.

This movement wil cease and the rod will automatically return to its point of departure as soon as the nozzle is no longer sealed, i.e., when there is no more pressure in the pipe 6 (i.e., when the pressure jet coming from channel 1 of the EM has again tipped towards 3).

At the end of the comparator arm opposite from the end on which the pulley C is mounted on, there is located a typically piston valve for opening and closing a valve controlling fluid flow from the conduit-line of pressure regulator D1 to the conduit line 6, which piston valve herein referred to as blade E is typically physically connected to and maneuvered by the workingend of the comparator arm as it is pivoted about a fulcrum point as shown in FIG. 1 in response to variations in tension of the yarn on the roller C, the closing action of the blade E sealing the nozzle T,, is composed of a strip fixed at the end of an arm the other end of this arm is fitted with a small guide pulley over which the yarn passes.

From the package to the needle, the yarn passes in the following order through the organs listed package,

wheel T, guide pulley interlocking with the arm, wheel D, needle (FlG. 1), not taking account of the guides and thread break stop motions.

The flow of the yarn as illustrated in FlG. 1 therefore follows from the feed spool B through the guide immediately before roller T and immediately following the roller T, and thereafter looped around the pulley C and onward to the roller D, etc.; the roller C is naturally biased against (such as by gravity) the pulling tension of the yarn loopedvtherearound such that movement of the pulley upwardly or downwardly carries with the moving pulley the end of the comparator arm on which end the pulley is fixedly mounted, with the comparator arm mounted between the opposing bellows diaphragms of S1 and S2 as a fulcrum point whereby the opposite end of the comparator arm causes the blade E piston valve to move to or fro to turn off or on the low pressure fluid to line 6. The rotation point of the arm is interlocking with the diaphragm of a bellows 8,, the displacement of this diaphragm being proportional to the value of the pressure reinjected into the bellows coming from the exit of the nozzle.'A resistance R' is inserted in the branch.

A second bellows S interlocking with the rotation point of the arm receives of the pressure injected into the bellows S through the intermediary of a resistance R (FIG. 4).

We thus obtain a regulator with proportional integral and derived action (F.I.D.).

The bellows S, gives rise to a negative reaction, whereas the bellows S creates a positive reaction.

The variation in pressure at the exit of the nozzle P, in function of the error at the blade is given by the ex pression below in which we find indead the propor tional, derived and integral part of the error. (see p. 6 of original) In this expression, Kr represents the transfer function of the bellows which transforms the pneumatic signal into a mechanical displacement.

, is a time constant equal to R C and z R C The circuit described above is very well suited, as one succeeds in maintaining the outlet tension, t,, of the yarn at a variation below 0.5 g for sudden changes of the order of 250 g upstream". However, its presents a major drawback for the simultaneous utilization of a large number of such circuits. Indeed, in order to have a sufficient pressure at the jack, a pressure very much higher than the nominal value has to be applied to the monostable element, which has the effect of reducing the output of this element, (already very low, 30 percent at nominal pressure) to an unacceptable value.

In this case, the monostable element, without mobile piece, is advantageously replaced by the assembly described below and specially designed for this purpose. It is composed of 3 parts A, B and C (FIG. 5).

The parts A and B are jammed against each other through the intermediary of a leaktight joint 1. In the midst of the mass of these two blocks, jammed to each other, a cylindro-conical space 2 has been turned. On both sides of this housing have been drilled two channels 3 and 4 terminating towards the outside by cones 5 and 6. In the space thus delimited, a rod 7, bearing two cones 8 and 9 at its ends and a bicone, 10, in its central part can move freely over a maximum distance of 1 mm.

The adjustment of the cones on the rod is effected in such a way that when the rod is at the bottom on the right, the cone 8 seals perfectly the exhaust seat 5 and the bicone 10, the right-hand part of the cylindroconical space 2. In this position, the control pressure P admitted by the channel 11 can escape only by the channel 12 towards the utilization, in this case a jack, whereas the channel 13 is at the discharge. Likewise, when the rod 7 is at the bottom on the left, the channel 12 is placed at the discharge, the bicone l seals the left-hand part of the cyIindro-conical space 2 and the cone 9 is applied against its seat 6. The control pressure is here conveyed towards the outlet channel 13. It is therefore possible, thanks to this assembly, to switch the inlet pressure I towards 12 or 13, depending on the position of the rod. The advantages of this system are manifold no limitation of the control pressure which may be very low or very high according to requirements,

- very high output, i.e., high ratio of the outlet pressure to the inlet pressure (90 percent),

- very simple and robust design, easily executable without any onerous commercial constraint, as for the monostable element without mobile piece.

This system might be reproached for being composed of mobile pieces diminishing the response time. In fact, although this remark is correct, it is nonetheless true that the latter remains small and very amply sufficient for the needs of the system. This performance is due in part to the slight displacement of the rod (1 mm).

It should be noted that the amplification developed for the special needs of the system forming the object of the present invention is neither an amplifier without mobile piece with Coanda effect, nor an amplifier of the diaphragm type, nor a 3/2 slide valve distributor with electric, mechanical or pneumatic control.

Block C constitutes the nozzle properly speaking the description of which has been given above. However, in this new assembly, tube 6 of FIG. 4 is no longer necessary, but is effected directly in the mass ofC (channel 14 of FIG.

The aperture of channel 14 is sealed by an extensible diaphragm 15 which may show a certain deflection when a pressure is applied to it. The diaphragm 15 is made interlocking with the' rod 7 (FIG. 6).

A more reliable system is obtained by replacing the extensible diaphragm 15 by a small cylinder 19 in which slides a piston 20 the pin of which is formed by the rod 7 of the pneumatic amplifier.

When the aperture 16 of the nozzle is sealed, the pressure applied in 14 displaces the piston and the rod 7 towards the left. As soon as the blade moves away from the nozzle, the pressure in the channel 14 is cancelled out and the piston is recalled to its departure position by the intermediary of the spring 17.

The channel 18 makes it possible to draw the pressure necessary for the execution of the RID. system as described above.

I claim:

1. For the establishing and maintaining of a constant predetermined tension on yarn fed from a spool prior to the utilization thereof by a sewing needle, a yarn tension regulator device comprising in combination: a support structure, spaced fixed yarn guides mounted on the support structure, a first revolvable roller, a first axis element for rotating the first roller mountedly thereon, a variably adjustable roller-mounting means mounted on said support structure and variable of the location of the first roller to and from positions relatively between the spaced fixed yarn guides whereby tensioning pressure on the yarn may be increased or decreased by to or fro movement respectively of the first axis element, power means for driving the first roller at a predetermined number of revolutions per minute, a second revolvable roller fixedly mounted in a stationary position upon said support structure opperatively connected to said power means for driving the second roller at a predetermined number of revolutions per minute, a pivot arm having a third roller mounted fixedly on one end of the pivot arm and having a valve piston operatively mounted on the opposite and working end of the pivot arm such that a valve may be turned on and off by to and fro movement of the working end, said pivot arm at a point intermediate between the opposite ends of the pivot arm being mountable on a pivot support, a fulcrum means mounted substantially fixedly on said support structure and said pivot arm being pivotably mounted on the fulcrum means, a fluid pressure means which may be turned on and off by said valve piston and which when turned on admits fluid pressure to said variably adjustable roller-mounting means for varying the location of the first roller from said to and from positions, said fulcrum means having said pivot arm mounted thereon such that the third roller is positioned for threading around the third roller yarn extending from said first roller to said second roller such that variations in yarn tension bring about to and fro movement of the third roller.

2. The yarn tension regulator device of. claim 1, and said fulcrum means including opposing bellow and diaphragms thereof with a pivot arm pivot structure mounted fixedly between the opposing diaphragms for movement therewith, and the movement of the opposing diaphragms and the bellows thereof being operatively connected to be controlled for to and fro movement by said variably adjustable roller-mounting means responsive to said valve piston movement.

3. The yarn tension regulator device of claim 2, in which the variably adjustable roller-mounting means includes a high pressure means providable of high fluid pressure and a valve therefor for the turning off and on of a piston cylinder, and including as a part of the variably adjustable roller-mounting means a piston cylinder and piston rod thereof operatively connected for effecting to and fro motion of the piston cylinder piston nected for response to variations in fluid pressure of rod responsive to the turning on and off respectively of said fluid pressure means in response to variations in the high pressure means valve, the on and off action of tension off the yarn on the pivoted third roller.

the high pressure means valve being operatively con- 

1. For the establishing and maintaining of a constant predetermined tension on yarn fed from a spool prior to the utilization thereof by a sewing needle, a yarn tension regulator device comprising in combination: a support structure, spaced fixed yarn guides mounted on the support structure, a first revolvable roller, a first axis element for rotating the first roller mountedly thereon, a variably adjustable roller-mounting means mounted on said support structure and variable of the location of the first roller to and from positions relatively between the spaced fixed yarn guides whereby tensioning pressure on the yarn may be increased or decreased by to or fro movement respectively of the first axis element, power means for driving the first roller at a predetermined number of revolutions per minute, a second revolvable roller fixedly mounted in a stationary position upon said support structure opperatively connected to said power means for driving the second roller at a predetermined number of revolutions per minute, a pivot arm having a third roller mounted fixedly on one end of the pivot arm and having a valve piston operatively mounted on the opposite and working end of the pivot arm such that a valve may be turned on and off by to and fro movement of the working end, said pivot arm at a point intermediate between the opposite ends of the pivot arm being mountable on a pivot support, a fulcrum means mounted substantially fixedly on said support structure and said pivot arm being pivotably mounted on the fulcrum means, a fluid pressure means which may be turned on and off by said valve piston and which when turned on admits fluid pressure to said variably adjustable roller-mounting means for varying the location of the first roller from said to and from positions, said fulcrum means having said pivot arm mounted thereon such that the third roller is positioned for threading around the third roller yarn extending from said first roller to said second roller such that variations in yarn tension bring about to and fro movement of the third roller.
 2. The yarn tension regulator device of claim 1, and said fulcrum means including opposing bellow and diaphragms thereof with a pivot arm pivot structure mounted fixedly between the opposing diaphragms for movement therewith, and the movement of the opposing diaphragms and the bellows thereof being operatively connected to be controlled for to and fro movement by said variably adjustable roller-mounting means responsive to said valve piston movement.
 3. The yarn tension regulator device of claim 2, in which the variably adjustable roller-mounting means includes a high pressure means providable of high fluid pressure and a valve therefor for the turning off and on of a piston cylinder, and including as a part of the variably adjustable roller-mounting means a piston cylinder and piston rod thereof operatively connected for effecting to and fro motion of the piston cylinder piston rod responsive to the turning on and off respectively of the high pressure means valve, the on and off action of the high pressure means valve being operatively connected for response to variations in fluid pressure of said fluid pressure means in response to variations in tension off the yarn on the pivoted third roller. 